Introduction
1-18 — Orbitor 3000 Reference Manual
To set up a Bandwidth on Demand installation, you would first connect the second link of the Orbitor Ethernet
bridge/router to a public circuit-switched network using the appropriate interface device. You would use high-speed
modems with telephone lines, terminal adapters with an ISDN network, or digital modems with switched digital services.
This second link would now be placed in a stand-by mode by setting the Link Activation to Conditional. The Link
Activation selection is found in the Link Setup Menu.
Now you must choose the throughput level that will be required for activating the stand-by link. The throughput level is
measured in percentage of use of the primary link. This percentage level is defined by the Up Threshold parameter in the
Link Activation Conditions Menu and may be set to any value from 50% to 100%.
A timer must be defined to determine the length of time to wait before bringing up the stand-by link. The Up Stability
Timer parameter in the Link Activation Conditions Menu is used to define how long in minutes (from 1 to 60) the main
link must exceed the threshold before the stand-by link is started.
Once the activation-throughput threshold has been determined and set, you must decide what the throughput threshold
will have to be to drop the second link and operate on the main link only.
The Down Threshold level is set in the Link Activation Conditions Menu and defaults to 10% lower than the Up
Threshold level. Remember that the down threshold looks at the total throughput (both links together) to determine if the
second link will be brought down. The Down Threshold is defined as the percentage of the main links bandwidth the
current total throughput represents. When the total throughput drops below the Down Threshold, the second link will be
dropped.
A timer must also be defined to determine the length of time to wait before dropping the stand-by link. The Down
Stability Timer parameter in the Link Activation Conditions Menu is used to define how long in minutes (from 1 to 60)
the combined links’ throughput must remain below the down threshold level before the stand-by link is stopped.
Disaster Recovery
To enable the disaster-recovery mode you simply set the Link Recovery parameter in the Link Activation
Conditions Menu to Enable. With link recovery enabled, the stand-by link will be activated whenever the main
link has dropped for more than 30 seconds. When the main link is re-established and stable for 30 seconds, the
secondary link will be placed in stand-by mode until the threshold level is exceeded or the main link fails again.
Time of Day Connect Application
In addition to the Bandwidth on Demand feature, the Orbitor Ethernet bridge/router has the ability to establish
link connections based on a specific time-of-day schedule. Either one or two links may be controlled using the
Time of Day feature. The Time of Day feature may also be used in conjunction with the Bandwidth on Demand
feature. It may be used in both Multipoint and Point-to-Point configurations.
Point-to-Point
One example of a Point-to-Point configuration would consist of a head office and a remote office. Cost
comparisons might reveal that it is less expensive to use a dial-up line during business hours only instead of a
permanent leased line.
One Orbitor Ethernet bridge/router will be installed at each office, and the link from each bridge/router will be
connected to a dial modem. Set the link operation of the bridge/router at the head office to Conditional, and then
enter a time schedule by using the Time Schedule option of the Link Activation Conditions Menu. The modem
connected to the head-office bridge/router will have an autodial number of the modem at the remote office. With
the time schedule set to have the link active from 8 am to 6 pm each day of the week, the Orbitor Ethernet
bridge/router will establish the link and keep it active during those hours only. The time selection may be made
in half-hour (30-minute) increments.
